Head in to almost any casino and slot machines will usually take up a major chunk of the gaming floor. Slots remain the most popular games in a casino, but are a fairly recent invention compared to many of the classic table games found in a casino. But slots have surged in popularity in the last century. From Las Vegas to mobile phones to video games, it just seems today’s gamblers can’t get enough of those “one-armed bandits.”

Today’s games don’t actually have those “arms” to initiate the reels on a slot and have come a long way since the early days of mechanical reels and inner workings. Today’s games are dynamic technological marvels that continue to advance and offer revolutionary technology that keep players coming back for more.

Keep reading as the blog delves into the world of slots and how they’ve innovated and transformed to meet the demands of today’s players. This article explores the past, examines the present, and looks to the future for new developments in a fast-paced and competitive industry.

Keep reading to learn about influential factors like RTP and volatility, and how technological advancements have launched slot machines into an era where anything seems possible.


1 – Early Games

It’s a good bet Charles Fey didn’t foresee how big slot machines would become when he designed his first Liberty Bell games in his San Francisco machine shop in the late 19th Century. When that first machine hit bars, restaurants, and cigar stores in the area in 1895, playing the slot was much different than what gamblers find today.

slots machines past

These machines were mostly utilitarian, a simple gaming machine that a person could play without the need of an employee or dealer to run the action. Fey ingeniously invented a machine that could do these seemingly simple tasks:

  • Accept a wager
  • Allow the player to initiate the game
  • Complete the betting game and determine a winner or loser
  • Pay out any winnings automatically
  • Allow the gambler to repeat the process

This may seem like a simple design in the age of computers and sophisticated software, but creating this using only mechanical inner workings was incredibly complex. The German immigrant had created a completely self-contained gambling device, a vast improvement over similar machines from the 1880s that required a staff member to pay out winners each time a win was registered.

“Unlike other contemporary coin-operated games, Fey’s slot machine paid out coins, not trade checks or tokens, and this made it both more appealing and more lucrative than traditional poker machines of the time,” notes Immigrant Entrepreneurship.

Fey’s machines, and subsequent competitors, paved the way for advancements that would follow throughout the 20th Century. The Liberty Bell introduced some of the slots basics that continue as part of the machines still today: three reels, paylines, varying symbols, automatic payouts, and more. He also introduced the “coin slot”, which gave the machines their name and is what they’re generally known by today.

These early machines sat on a countertop and offered a single payline. After depositing a nickel, a player hoped to line up certain symbols across the payline and be rewarded with a payout. These early machines also set the trend for offering varying payout amounts including one that stood out among the others, a precursor to the jackpot.

Three bells paid out the most – a jackpot of 20 coins. The lowest winning spin came on two horseshoes, which paid out 5 cents. Another precursor to today’s hoopla when securing a large payout, a bell rang when a player hit the game’s highest payout.

So how did the inner workings of the game produce slot machine results? Each reel had 10 stops which created 1,000 different combinations. Along with the namesake “liberty” bells, the games featured several other symbols including horseshoes, stars, spades, diamonds, and hearts. Many of these are still featured on many slot machines today.

The Liberty Bell also featured a return to player percentage (known today in the industry as “RTP”), paying out 86% of all coins wagered in the machines. The machines were an instant hit in the San Francisco area, but Fey couldn’t keep up with demand while manufacturing each slot in his Bay Area machine shop.

Competitors soon stepped in to meet growing demand and move into new markets all across the U.S. But Fey’s initial invention launched an industry that would one day be worth billions of dollars. Those early designs and ideas launched a gambling revolution that would see massive growth and innovation over the next century-plus.


2 – 20th Century Innovations

The greatness of Fey’s invention may have been the simplicity and passivity in which one could gamble. Someone doesn’t have to know how to play blackjack, know the rules of poker, or understand seemingly complex betting on games like craps. A gambler simply takes a seat, drops in a quarter, and waits for the reels to come to a stop.

Not a winner? It’s easy to repeat the process and someone can take their time and gamble at their own pace. This entire process appeals to many players still today. But in the intervening few decades after those early machines, slots didn’t see many major changes. They still made use of mechanical workings to get those reels spinning.

However, one improvement was in the cabinets that house the slots. As seen in early 20th Century furniture and housewares, these games began featuring more intricate craftsmanship. From the turn of the century up through the 1950s, many games featured metal housings and often included engravings, colors, graphics, and more. Some of these machines looked like real works of art. For example, here’s a look at a few vintage slots from this time period that are also now collector’s items.

  • Jennings Standard Chief Nickel Slot – This slot from the 1940s featured some exquisite designs and contours, highlighted in chrome and red. The profile of the Native American chief on the front of the machine really made this game stand out. The Jennings Standard Chief featured traditional bells and fruits on a single payline.
  • Mills War Eagle Nickel Slot – Mills was an early competitor with Fey and produced some brilliant machines, including the War Eagle in the early 1930s. The game impresses with some true artistry, with an amazing war eagle spreading its wings on the front of the machine. The red, black, silver, and yellow color scheme really stands out. The War Eagle came with a single payline and traditional bells and fruit symbols.
  • Jennings Silver Club Sports Dime Slot – This is another machine from the 1930s, but showed that manufacturers were advancing beyond the traditional nickel game. This game upped the ante to 10 cents and also featured some cool artwork with an athletics theme. Despite the creativity the industry was seeing aesthetically, manufacturers were still using the traditional fruit symbols. Perhaps players had just grown so accustomed to these “fruit slots” that many manufacturers didn’t feel the need to change.

Many of these machines were still found in similar sizes as those early bartop style machines that Fey debuted in the 1890s. However, many now were placed atop fin wooden cabinets to make them playable while standing up (or sitting at a barstool). In coming years, manufacturers would eventually combine the main slot and the cabinet into much more advanced games or line the slots up side by side in long rows in modern casinos.

slot machines land-based

In the 1950s and ‘60s, Las Vegas began to boom with properties like the Flamingo and Caesars Palace attracting visitors from around the world. Those shiny slots were becoming a bigger part of the gambling business and began seeing more innovation than seen in the last 50 years. Players began seeing other key additions like multi-game payouts, four-reel machines, and multiple paylines. This last innovation proved popular and now offered players more ways to win and considerably more variation.

Denominations began going up as well. Most machines began accepting slot tokens, many of which represented $1 and more. During this time, players began seeing even more creativity and diversity in those one-armed bandits. That “one arm” notion began to change as well. At least partial electromechanical games began debuting in the 1940s, but Bally’s then released the industry’s fully electromechanical game in 1963.

The game was called “Money Honey” and gamblers still pulled a lever, but the game was fully electrically operated. Money Honey also exemplified how games were becoming larger during this period and beginning to look more similar to the modern machines today. The game featured a more boxy look with a siren on top for when someone cashed in on a big score.

Aesthetically, games like Money Honey also began utilizing more lights and sounds on the games’ facade, beckoning gamblers to take a shot at a big payout and adding a bit more of the “bright lights” of Las Vegas right on the machine. Money Honey proved immensely popular for Bally’s and inspired other manufacturers to release more and more electromagnetic slot machines.

“Like Henry Ford’s Model T, this three-reel electromechanical slot machine broke new ground, forever changing the landscape of the gaming industry,” Bally’s noted of the game’s importance to the company and the industry. “The two innovations that the game brought to the casino industry were its reliable electronically controlled construction and the incorporation of a “bottomless” motor-driven payout hopper capable of automatic payouts of up to 500 coins without the use of an attendant. For the next 12 years, Money Honey in its many variations would become the flagship game of Bally Manufacturing’s slot machine division.”

It’s important to note that many of these games continued to stick with those traditional symbols like fruits, bells, 7s, bars, and more that debuted all the way back in the 1890s. Money Honey saw some more creativity when it came to the design of these traditional icons, but manufacturers seemed reluctant to vary too much. But gaming companies would continue to accelerate slot machine creativity and innovation in the coming years – and computer and video technology would play a major part in that.


3 – The Computer Age

As slot machines grew in popularity throughout the 20th Century, the games saw considerable changes and innovation. That ramped up even more with the use of technology. As computer technology became more available, manufacturers began seeing the possibilities available when designing slot machines and this kickstarted a real renaissance in the industry over the next few decades.

That innovation included the first video slot being released in 1963 with the debut of a game called Automatic Blackjack. The slot didn’t actually offer the same type of slot game visitors to Las Vegas were accustomed to playing. But that technology also soon found its way to more traditional slot machines. These games initially didn’t gain traction, but video poker brought in plenty of gamblers in the 1970s and ‘80s, leading more players to consider video slot options as well.

“When legalized casino gambling dawned in America, in the era of Bugsy Siegel and Meyer Lansky, primitive slot machines – those one-armed bandits – served as little more than mechanical babysitters for the wives and girlfriends of high-roller card and dice players,” the Atlantic magazine noted in 2008 about the growth and expanding technology in the industry. “And for decades thereafter, even as casinos low-rolled their way into the mainstream, gambling itself retained an air of disrepute (charming though it could be) that tended to keep decent folks away. But the recent proliferation of highly sophisticated, computerized, brightly lit, singing-and-talking slots has done away with any lingering social stigma attached to the betting life. Some statistics, random but telling:

“America now has twice as many publicly available gambling devices that take money—slot and video-poker machines and electronic lottery outlets – as it does ATMs that dispense it. In the past fifteen years the number of such devices has grown fivefold, to more than 740,000, and is still mounting.”

Games began seeing on-screen “reels,” video clips, improved sound effects, and much more. Players would eventually see larger screen games and better design. After so long of the industry being seemingly unchanged, the technological advances on slots would boom beginning in the 1980s.

Also, when it comes to modern slot symbols, the games have moved well beyond simple fruits, bars, and 7s. Today’s games feature symbols of every color, variety, and feature. Many games come with unique narrative formats that give players a more interactive experience than those early games. Entertaining and humorous themes add to this and keep players entertained.

Computer innovations made linking slot machines together across a wider area a real possibility for the first time. In 1986, International Game Technology (IGT) debuted the first-ever progressive slot machine. Megabucks revolutionized the industry with a small portion of all coin-in going into the progressive prize pool. Eventually these prize pools would be spread across regions, states, and more. That progressive prize pools until a player cashes in for the ultimate prize.

For the first time, gamblers had a chance to win some truly eye-popping jackpots and that trend continues today with Megabucks remaining one of the most popular progressives in the industry. On Feb. 1, 1987, the reels aligned just right for one lucky player to become the world’s first progressive jackpot winner. The new millionaire cashed in for almost $5 million, equal to more than $13 million in today’s dollars.

The early 1980s also saw some of the first casino rewards systems. Casinos could more easily track their guests’ play and a player card could actually be slid into a slot machine. This enhanced the old “comp system” that rewarded loyal players with free meals, rooms, prizes, and more. These new reward cards became a major part of playing slots and some operators even began offering free play to players as a reward – and a way to bring players coming back in the doors.

In 1996, WMS Industries introduced the game “Reel ‘Em.” This game has the distinction of becoming the first video slot with a second-screen bonus round. Players would be sent to a completely different screen for the extra game. This unique addition proved incredibly popular with players and most games now feature bonus rounds, free spins, wild symbols, prize wheels, pick ‘ems, and other bonuses to enhance the gameplay and to keep players interested.

This was a huge addition to the world of slots, and by the mid-1990s, slots already accounted for 70% of casino revenue and up to 70% of gaming floor space. Slots were quickly becoming a multi-billion business and attracting gamblers in droves.


4 – Massive Growth & Technological Advancements

Today’s slots offer even more options for players. Numerous resources are available when determining a player’s personal game of choice or a slot that might fit better with their bankrolls. Players can easily find key information like the RTP (return to player) for certain casinos, slots, and even more specific segments like different stakes.

Game statistics related to a game’s volatility are also available. Slot manufacturers offer differing levels of volatility to fit with differing player affinities. A slot with higher volatility may reward players with winnings less often but also tends to pay out larger amounts when a player does find a winning spin. Think of games with larger jackpots and progressive when it comes to highly volatile games.

Games with lower volatility reward payouts more often but in smaller amounts. These can create more winnings for players but still may not mean a player will find a winning session. A slot’s volatility has become more important within the industry in recent years.

In the 2000s, manufacturers began reaching beyond the traditional idea of what a slot machine could be. Licensing popular movies, television shows, rock stars, and other pop culture icons have become regular in the industry. These games incorporated video clips from the actual movies and TV shows (such as Jurassic Park) or songs and concert footage from popular singers and bands.

Themes advanced as well, offering games featuring mythology, adventure, history, and anything else that might interest players. If a player has a particular interest, the chances are that there’s a slot for that. Slot technology also continues to advance with:

  • High-definition and 4K video technology
  • Curved monitors
  • Larger and more advanced cabinets
  • High-tech speakers and surround sound
  • Computer algorithms
  • Random number generators

The 2000s also saw the rise of slot streaming with popular players like Brian Christopher going from slot to slot and casino to casino to show off some of the latest games and show how they work. These YouTubers attracted millions of viewers simply to watch the player hosts cash in for some big wins or strike out. These slots vlogs brought a new dynamic to the games, with casinos and slot developers even catering to these growing audiences.


The industry continues to grow and expand, and players just can’t seem to stop spinning those reels and checking out some of the latest and greatest innovations.

playing online slots


5 – Looking Ahead

As slot manufacturers advance and grow their products, manufacturers continue offering more and more creative elements, designs, features, sound, and more. When looking ahead, expect even more pop culture licensing, at least in the near term. But when looking ahead, what more can slot manufacturers offer when it comes to technology and unique gameplay? Here’s a look at some trends on where the slot machine industry may be heading.

Virtual Reality and 3-D – High-definition options continue to grow, and as manufacturers make use of curved screen technology and other technology, this type of slot gaming might be around the corner. VR is becoming more and more popular with breakthroughs in goggles regularly coming from companies like Apple and others. These alternate worlds may offer a completely different slot experience, transporting players to other worlds and even new gaming styles.

Artificial intelligence – AI is playing a larger role in numerous industries, and can gaming be far behind? Perhaps the technology could make an even more intuitive experience for players? Savvy gaming industry insiders are already working to see how this high-tech machine learning could better serve guests and make even more creative games.

Holograms – Music fans around the world are already attending concerts of long-dead singers via hologram. This technology continues to improve, and perhaps holo-slots could be in the works. These additions could offer a more immersive experience as operators look for the next big thing.

Expanded narratives – Many games are already making use of more story-like approaches, but perhaps operators may be looking to expand this approach even more. With streaming content available right on someone’s mobile phone, slot developers may want to get on the bandwagon and make players feel like they are in the middle of a movie themselves. This may offer companies the chance to completely redefine the way players think of slot machines.

Skill-based games – Some companies have already moved in this direction, but with a couple of generations of people so enmeshed in traditional video games as well as mobile games, this aspect of slots may be destined for even more growth and advancement.

Mobile and online gaming – Platforms continue to raise the bar when it comes to their online offerings, whether in the real-money gaming realm or simply using play money for fun. This aspect of the industry continues to show major growth, and companies continue working to make their products stand out. That has even included the ability to play real slots via a computer or mobile phone in the same way players can also play live dealer table games in some jurisdictions online. It’s a good bet some of these options listed here may be coming to the slot sites world as well.

Cashless gaming – This is already a reality in some casinos, but no doubt will continue to grow in the coming years. Players can spin some reels on their favorite slots without worrying about actually carrying cash. This comes with some interesting questions, however. How will gamblers actually embrace this type of slot gaming? Some may believe this isn’t a wise method to play when it comes to watching a player bankroll. This may bring about responsible gaming concerns among some industry and gamblers as well. However, some casino properties are already moving forward with this plan, and perhaps there will be some responsible gaming options incorporated as seen in online gaming.

In such a changing world and in such a creative industry, there are no doubt numerous other possibilities for the future of slots. Some engineers and software developers are probably already working on the next piece of technology that will resonate with casinos and players alike.


6 – Frequently Asked Questions

When were slot machines invented and who designed the first game?
German immigrant Charles Fey is credited with creating the first slot machine in his San Francisco machine shop in the late 1800s with his first fully-functional Liberty Bell slot debuting in 1895. For the first time, players could place a wager, initiate a game, and receive a payout without the need for an employee or dealer.

What were early slot machines like?
Early slot machines were mechanical devices that featured three reels and a single payline. Players would deposit a coin and hope for certain symbols to align across the payline to win a payout. These machines had simple designs and often featured symbols like fruits, bells, and horseshoes.

How have slot machines evolved over time?
Slot machines have evolved significantly over time. They have transitioned from mechanical devices to electromechanical and fully electronic machines. Technological advancements have introduced video slots, bonus rounds, development of progressive jackpots, improved graphics and sound, and more diverse themes and symbols. The rise of the internet has also led to the development of online slots and mobile gaming.

What are some future trends in slot machine technology?
Some future trends in slot machine technology include virtual reality and 3D gaming, the integration of artificial intelligence, holographic displays, expanded narratives and storytelling, skill-based games, advancements in mobile and online gaming, and the adoption of cashless gaming systems. These trends aim to enhance the player experience and offer new ways to engage with slot machines.

Are there responsible gaming concerns with the advancement of slot machine technology?
As slot machine technology advances, there can be responsible gaming concerns, particularly with the introduction of cashless gaming and online platforms. It becomes essential for operators and regulators to implement responsible gaming measures and tools to ensure the well-being of players and prevent excessive gambling behavior. It's important to balance technological advancements with responsible gaming practices.

Sean Chaffin is a freelance writer in Crandall, Texas. His work appears in numerous websites and publications. Follow him on Twitter @PokerTraditions. He is also the host of the True Gambling Stories podcast, available on iTunes, Google Play, TuneIn Radio, Spotify, Stitcher, PokerNews.com, HoldemRadio.com, and other platforms.